Joint assemblies are well known in mechanical systems. Many joint assemblies are designed to permit pivotal movement of the connected components with respect to each other. Examples of prior art joint assemblies include:
U.S. Pat. No. 2,704,681 to Fischer PA1 U.S. Pat. No. 4,561,797 to Aldridge PA1 U.S. Pat. No. 4,669,907 to Patton PA1 U.S. Pat. No. 4,308,419 to Fredriksson PA1 U.S. Pat. No. 1,903,863 to Hayden PA1 a first portion formed with a first aperture; PA1 a second portion formed with a second aperture, said first and second apertures being alignable; PA1 a recess formed about the second aperture; PA1 a shaft insertable through the first and second apertures; PA1 bearing means formed adjacent one end of the shaft; PA1 a retaining member releasably mountable to the other end of the shaft; PA1 a spacing member insertable between the first and second portions to separate the portions to an extent such that the bearing means of the shaft engages and retains the first portion on the shaft and the retaining member mounted to the shaft is positioned within the recess of the second portion to define a second bearing means that engages and retains the second portion on the shaft to releasably and rotatably lock together the first and second portions for rotation with respect to each other about an axis defined by the shaft.
Joint assemblies find particular application in lifting loads. Once lifted and supported, it is desirable to be able to manoeuvre the load by rotation or pivoting of the joint assembly. It is important to have a joint assembly that is reliable and sufficiently robust to safely handle very heavy loads. It is also preferable that the joint assembly be of relatively simple construction so that it can be easily broken down for maintenance and repair.